Chemical synthesis of H3-25-OH-D3 and H3-1,25-(OH)2D3 of high specific activity (100 Ci/mmole) will be attempted and if successful, used to study possible receptor proteins and further metabolism. Metabolites of 1,25-(OH) 2D3 and 25-OH-D3 which have been discovered in intestine and kidney will be isolated in pure form and identified. Work will commence on synthesis of affinity columns for vitamin D and will continue on the isolation of the components of the 25-OH-D3-1alpha-hydroxylase. High specific activity H3 retinoic acid and retinol will be synthesized and used to label metabolites for isolation. Attempts will be made to isolate differentiated epithelial cells and basal cells from rat epithelial tissue in preparation for a study of the role of vitamin A in epithelial differentiation. Investigation of the properties of the prothrombin precursor proteins and function of vitamin K in the vitamin K dependent carboxylation reaction will continue. Studies on the effects and interaction of vitamin E and selenium in protecting against oxidant damage will continue with the primary focus on glutathione peroxidase and on a variety of agents capable of producing oxidant damage.